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A fuel tank full of water

Forget cars fuelled by alcohol and vegetable oil. Before long, you might be able to run your car with nothing more than water in its fuel tank. It would be the ultimate zero-emissions vehicle.

While water, plain old H2O, is not at first sight an obvious power source, it has a key virtue&colon; it is an abundant source of hydrogen, the element widely touted as the green fuel of the future. If that hydrogen could be liberated on demand, it would overcome many of the obstacles that till now have prevented the dream of a hydrogen-powered car becoming reality. Producing hydrogen by conventional industrial means is expensive, inefficient and often polluting. Then there are the problems of storing and transporting hydrogen. The pressure tanks required to hold usable quantities of the fuel are heavy and cumbersome, which restricts the car’s performance and range.

Tareq Abu-Hamed, now at the University of Minnesota, and colleagues at the Weizmann Institute of Science in Rehovot, Israel, have devised a scheme that gets round these problems. By reacting water with the element boron, their system produces hydrogen that can be burnt in an internal combustion engine or fed to a fuel cell to generate electricity. “The aim is to produce the hydrogen on-board at a rate matching the demand of the car engine,” says Abu-Hamed. “We want to use the boron to save transporting and storing the hydrogen.” The only by-product is boron oxide, which can be removed from the car, turned back into boron, and used again. What’s more, Abu-Hamed envisages doing this in a solar-powered plant that is …